During rotary drilling, the torque applied at a top drive of a drilling rig is often out of phase with the rotational movement at the bottom-hole assembly (BHA) of the drill string due to an elasticity of the material of the drill string. This causes the drill string to yield somewhat under the opposing loads imposed by the rotational force at the top drive and friction/inertia at the end where the bit is located (e.g., the BHA). This causes undesirable resonant motion to occur between the top drive and the BHA. Further, as the drill string winds up along its length due to the ends being out of phase, the torque stored in the winding may exceed any static friction, causing the drill string near the bit to slip relative to the wellbore sides at a high (and often damaging) speed.
Current approaches to stick-slip mitigation adjust a rotation speed during the rotary drilling to reduce the chance of stick-slip and/or other vibrations. Thus, these approaches modulate top drive rotations per minute (RPM) to mitigate vibration occurring down hole. The modulation of RPM is done at the top drive and is based on configuring the top drive control system to match the impedance of the drill string. These approaches are therefore top-drive specific (or even, in some instances, variable frequency drive specific). As a result, settings at one top drive or variable frequency drive cannot be easily applied to a different top drive or variable frequency drive.
Other approaches to stick-slip mitigation provide damping materials down hole near the drill bit. However, these approaches address the issue by attempting to absorb vibration down at the drill bit, not by matching impedance at the top drive so as to prevent standing waves from reflecting back. Further, these approaches are more costly because any replacement requires tripping the entire drill string in order to access the BHA where these approaches are implemented.
The present disclosure is directed to systems, devices, and methods that overcome one or more of the shortcomings of the prior art.